JP2007198607A - One-way clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide compatibility between wear resistance, and stabilization of state change-over operation in a wide temperature range from a low temperature to a high temperature, in a one-way clutch. <P>SOLUTION: The one-way clutch 3 is interposed in an opposing annular space between an outer ring 11 and an inner ring 12 concentrically arranged in the outside and inside of a radial direction. A lubricant used in an operation portion of a state change-over element 13 is composed by mixing an urea-based thickener into an ester-based or a synthetic oil-based base oil comprised by setting a coefficient of pressure viscosity (at 25°C) at 12GPa<SP>-1</SP>or more. By the lubricant, movement of the state change-over element 13 stabilizes even in a low temperature, and wear of the state change-over element 13 and an operation face is suppressed even in a high temperature. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a one-way clutch. This one-way clutch is used, for example, for a feed mechanism of various devices, or an auxiliary machine pulley such as an automobile alternator, a compressor for an air conditioner, a water pump, and a cooling fan.

  The one-way clutch switches between a locked state in which an outer ring and an inner ring disposed concentrically inside and outside in the radial direction are synchronously rotated and a free state in which the outer ring is relatively rotated.

  Here, for example, in a one-way clutch of a type using rollers, wedge-shaped spaces are provided at several circumferential positions in the radially opposed space between the inner and outer rings, and the rollers are arranged in the wedge-shaped spaces. The wedge-shaped space is formed by, for example, a cam surface formed of a concave curved surface that is recessed outward in the radial direction, provided at several circumferential positions on the inner peripheral surface of the outer ring, and an outer peripheral surface of the inner ring that is disposed radially inward. .

By the way, as a lubricant used for a clutch function portion of a one-way clutch, urea-based grease is generally used (see Patent Document 1).
JP-A-3-249435 (see upper right column on page 2)

  In the conventional example described above, the inner and outer rings are integrated by the frictional force of the rollers in the locked state, but there are cases in which both engagement and wear resistance cannot be achieved in a wide temperature range from low temperature to high temperature. Specifically, the roller has poor meshing properties at low temperatures and wear resistance at high temperatures.

  By the way, the applicant of the present application is equipped with a one-way clutch in the alternator, and when the rotation speed of the crankshaft decreases, the rotation of the alternator rotor is continued by its inertial force to increase the power generation efficiency. Although such a structure has been proposed, the vibration of the engine is almost always transmitted to the alternator pulley via a belt that rotationally drives the pulley, so that wear resistance is particularly likely to deteriorate. .

  In view of such circumstances, an object of the present invention is to make it possible to achieve both stabilization of state switching operation and wear resistance in a wide temperature range from low temperature to high temperature in a one-way clutch.

A one-way clutch according to a first aspect of the present invention is a one-way clutch that switches between a state in which two annular members disposed concentrically in and out of a radial direction are synchronously rotated and a state in which they are rotated relative to each other. The lubricant used for the operating part is pressure viscosity coefficient (at 25 ° C.) 12 GPa ⁻¹ or more and 64.4 GPa ⁻¹ or less, consistency (at 25 ° C.) 240 to 310, traction coefficient 0.02 or more and 0.066 or less It is a component in which a urea-based thickener is blended with an ester-based or synthetic oil-based base oil.

  The one-way clutch according to the invention of claim 2 is a roller in which the state switching element of claim 1 is disposed so as to be able to roll in a wedge-shaped space formed between the two annular bodies.

 The one-way clutch according to the invention of claim 3 is such that the consistency (at 25 ° C.) of the lubricant of claim 1 or 2 is 240 to 310 and the traction coefficient (at 25 ° C.) is 0.02 or more. The blending ratio of the base oil to the thickener is set.

  As described above, in the present invention, the components of the lubricant to be used are selected, so that the movement of the state switching element becomes stable even at a low temperature, and the state switching element and the operating surface are worn even at a high temperature. It becomes difficult.

  In particular, if the state switching element is a roller as in the second aspect of the invention, slipping is less likely to occur when the roller rolls against the narrow side of the wedge-shaped space.

  Further, if the characteristics of the lubricant are specified as in the third aspect of the invention, the movement of the state switching element such as a roller is further stabilized.

  According to the first to third aspects of the present invention, it is possible to achieve both stabilization of the state switching operation and wear resistance in a wide temperature range from low temperature to high temperature, thereby contributing to improvement in reliability and life.

  In particular, in the invention of claim 2, the state switching element described above is a roller, and slipping when the roller rolls with respect to the narrow side of the wedge-shaped space can be prevented.

  In the invention of claim 3, the characteristics of the lubricant are specified, and the operation stability of the state switching element such as a roller is further stabilized.

 The present invention will be described in detail based on embodiments shown in the drawings.

 1 to 3 show one embodiment of the present invention. FIG. 1 is a longitudinal front view of a one-way clutch, FIG. 2 is a developed plan view showing a cage and rollers accommodated therein, and FIG. 3 is a front view of the one-way clutch.

 In the figure, reference numeral 10 denotes the entire one-way clutch. The one-way clutch 10 includes an outer ring 11, an inner ring 12, a plurality of rollers 13, a cage 14, and a plurality of coil springs 15.

  The outer ring 11 and the inner ring 12 are disposed concentrically inside and outside in the radial direction. Among these, cam surfaces 12 a are formed at several places on the outer peripheral surface of the inner ring 12 to form a wedge-shaped space that narrows the facing interval toward the circumferential direction one side with the outer ring 11. The cam surface 12a is formed in a flat key shape, so that the outer shape of the inner ring 12 looks like a polygon.

  The plurality of rollers 13 are disposed so as to be able to roll in the circumferential direction in a wedge-shaped space formed between the cam surface 12 a and the inner peripheral surface of the outer ring 11.

  The retainer 14 is externally fitted to a cylindrical portion partially remaining in the circumferential direction on the outer peripheral surface of the inner ring 12, penetrates radially inward and outward in a region corresponding to each cam surface 12 a of the inner ring 12, and a plurality of rollers. 13 each has a pocket 14a to be individually stored. The retainer 14 is fixed to the inner ring 12 by fitting a convex part 14 b provided at one end in the axial direction with a slit-like concave part 12 b provided in the inner ring 12.

  The plurality of coil springs 15 are accommodated in a compressed state in a state adjacent to the rollers 13 in the circumferential direction in the respective pockets 14 a of the cage 14. Each of these coil springs 15 presses each roller 13 toward the narrow side of the wedge-shaped space by its extension restoring force. In particular, in this embodiment, in order to avoid the skew of the roller 13 as the coil spring 15 described above, an elliptical shape as viewed from the end face is used so that the coil spring 15 is applied to an area as wide as possible in the axial direction of the roller 13. I am doing so.

  Next, the operation of the one-way clutch 10 will be described.

  First, when the outer ring 11 is driven to rotate in only one direction and the inner ring 12 is driven, the roller 13 is rolled to the narrow side of the wedge-shaped space when the rotational speed of the outer ring 11 is increased. Thus, the inner ring 12 is integrated with the outer ring 11 and rotates synchronously. This state is a locked state.

  However, when the rotational speed of the inner ring 12 becomes higher than that of the outer ring 11 due to a decrease in the rotational speed of the outer ring 11 or the like, the roller 13 resists the spring force of the coil spring 14 and rolls toward the wider side of the wedge-shaped space. As a result, the outer ring 11 and the inner ring 12 rotate relative to each other. This state is a free state.

  When the outer ring 11 is used in an arbitrarily rotating manner in both directions, when the outer ring 11 rotates in the clockwise direction in FIG. 1, the inner ring 12 is in the same direction as the outer ring 11. When the outer ring 11 rotates counterclockwise in FIG. 1, the outer ring 11 enters a free state as described above, and no rotational power is transmitted from the outer ring 11 to the inner ring 12. The inner ring 12 is not rotated.

  By the way, for the one-way clutch 10 described above, for example, a lubricant in which a urea-based thickener is mixed with an ester-based or synthetic oil-based base oil is used.

For the base oil of the lubricant pressure viscosity coefficient 25 ° C. at 12 GPa ^-1 or more (preferably 16 GPa ^-1 or more) are selected ones. The blending ratio of the base oil and the thickener in the lubricant is such that the consistency is 240 to 310 (preferably 270 to 290) at 25 ° C., and the traction coefficient is 0.02 or more (preferably 0.00) at 25 ° C. 04 or higher).

  Here, since the engagement property and wear resistance when various lubricants are used for the one-way clutch 10 described above were evaluated by experiments, they will be described.

  In this experiment, a total of eight lubricants including Embodiments 1 to 4 shown in Table 1 below and Comparative Examples 1 to 4 shown in Table 2 below were prepared.

In the lubricants of Embodiments 1 to 4, the base oil is ester oil or synthetic oil, the pressure viscosity coefficient (at 25 ° C.) is 12 GPa ⁻¹ or more, the consistency of the lubricant (at 25 ° C.) is 240 to 310, and lubrication is performed. The traction coefficient of the agent (at 25 ° C.) is specified to be 0.02 or more.

  The lubricants of Comparative Examples 1 to 4 use the base oil and the thickener specified in the present invention, but the lubricant of Comparative Example 1 sets the consistency and traction coefficient outside the scope of the present invention. The lubricant of Comparative Example 2 has a pressure viscosity coefficient and consistency set outside the scope of the present invention, and the lubricant of Comparative Example 3 has a traction coefficient set outside the scope of the present invention. Furthermore, the lubricant of Comparative Example 4 has a pressure viscosity coefficient set outside the scope of the present invention.

上記表での性能評価について、かみ合い性は、低温雰囲気（−２０℃〜−４０℃）でのロック時において外輪１１の回転に対する内輪１２の回転の追従状態を調べることにより行い、また、耐摩耗性は、高温雰囲気（１００℃〜１２０℃）での動作後における内輪１２のカム面１２ａや外輪１１内周面の摩耗状態を調べることにより行った。かみ合い性に関して、○は、外輪１１の回転に対する内輪１２の回転が安定して追従している場合、△は、外輪１１の回転に対する内輪１２の回転がしばしば追従しなくなるような不安定な場合、×は、外輪１１の回転に対する内輪１２の回転が追従しない場合を示している。また、耐摩耗性に関して、○は、ほとんど摩耗なしの場合、△は、摩耗が見られる場合、×は、摩耗が非常に大きい場合を示している。

Regarding the performance evaluation in the above table, the meshing property is determined by examining the follow-up state of the rotation of the inner ring 12 with respect to the rotation of the outer ring 11 when locked in a low temperature atmosphere (−20 ° C. to −40 ° C.). The properties were determined by examining the wear state of the cam surface 12a of the inner ring 12 and the inner peripheral surface of the outer ring 11 after operation in a high temperature atmosphere (100 ° C. to 120 ° C.). Regarding the meshing property, ◯ indicates that the rotation of the inner ring 12 stably follows the rotation of the outer ring 11, and Δ indicates that the rotation of the inner ring 12 does not frequently follow the rotation of the outer ring 11, X indicates a case where the rotation of the inner ring 12 does not follow the rotation of the outer ring 11. Regarding wear resistance, ◯ indicates that there is almost no wear, Δ indicates that wear is observed, and X indicates that wear is very large.

  As a result, in the lubricants of Embodiments 1 to 4, the meshing operation of the rollers 13 was smooth over a long period of time, and no significant wear occurred on the rollers 13 and the cam surface 12a. The meshability is slightly reduced, the wear resistance of the lubricant of Comparative Example 2 is remarkably reduced, the meshability of the lubricant of Comparative Example 3 is remarkably reduced, and the lubricant of Comparative Example 4 is further reduced in meshability and wear resistance. Both of these results decreased slightly.

From these results, when the pressure viscosity coefficient (at 25 ° C.) of the base oil is set to 12 GPa ⁻¹ or more, the pressure resistance increases and the oil film is less likely to break, and the consistency (at 25 ° C.) is increased. When it is set to 240 to 310, the fluidity tends to increase and the wear suppression effect tends to increase. Further, when the traction coefficient (at 25 ° C.) is set to 0.02 or more, the roller 13 tends to be less slippery and has better engagement properties. It can be said that

  In the one-way clutch 10 described above, the movement of the roller 13 is stable even at a low temperature, and the roller 13 and its contact partner (the cam surface 12a of the inner ring 12 and the inner peripheral surface of the outer ring 11) are not easily worn even at a high temperature. This will contribute to the improvement of reliability and service life.

 By the way, the above-described one-way clutch 10 can be incorporated in pulleys of various auxiliary machines mounted on an engine such as an automobile. Specifically, an example in which the one-way clutch 10 is incorporated in a pulley of an alternator as an auxiliary machine of an automobile is shown in FIG. FIG. 4 is a vertical side view of a pulley unit incorporating a one-way clutch.

  In the figure, A indicates the whole pulley unit, 1 is a pulley, 2 is a rotating shaft, and 3 and 3 are rolling bearings. The pulley 1 is provided with a belt groove 1a around which the drive belt B is wound. The rotating shaft 2 becomes an input shaft of the alternator. The rolling bearings 3 and 3 are disposed on both sides in the axial direction of the opposed annular space between the pulley 1 and the rotating shaft 2 and mainly bear a radial load, and both are general deep groove ball bearings.

  In the illustrated pulley unit A, the seal member 5 is mounted only on the axially outer end side between the inner and outer rings of the two rolling bearings 3, 3. The rolling bearings 3 and 3 are sealed, and a common lubricant is used for the one-way clutch 10 and the two rolling bearings 3 and 3, respectively.

  In the illustrated pulley unit A, a one-way clutch 10 is disposed in an opposed annular space between the pulley 1 and the rotating shaft 2. In this example, the outer ring 11 of the one-way clutch 10 is fitted to the pulley 1 and the inner ring 12 of the one-way clutch 10 is fitted to the rotary shaft 2 by press fitting.

  Such a pulley unit A is used in such a form that the pulley 1 is rotated only in one direction and the rotation speed is arbitrarily changed. The operation is the same as that described for the operation of the one-way clutch 10 described above.

  That is, when the pulley 1 is rotated in the required direction by the belt B, the one-way clutch 10 is locked as the rotation rises, and the rotational power from the pulley 1 to the inner ring 12 and the rotating shaft 2 is substantially 1: 1. To communicate at a rate of.

  However, if the rotational speed of the pulley 1 temporarily decreases in the process of increasing the rotation of the pulley 1, the rotational speed of the inner ring 12 and the rotating shaft 2 is instantaneously faster than the rotational speed of the pulley 1 due to the rotational inertia force. The one-way clutch 10 becomes free and the transmission of rotational power from the pulley 1 to the rotary shaft 2 is cut off.

  Thereafter, when the rotational speed of the pulley 1 becomes faster than that of the rotating shaft 2, the one-way clutch 10 is locked again, so that rotational power is transmitted from the pulley 1 to the rotating shaft 2.

  As described above, even if the rotational speed of the pulley 1 fluctuates (pulsates), the one-way clutch 10 is appropriately switched between the locked state and the free state, and the pulsation of the rotational speed of the pulley 1 is rectified. Thus, the rotation shaft 2 is transmitted linearly. In addition, when the rotational speed of the pulley 1 is decelerated, the one-way clutch 10 is in a free state so that the rotary shaft 2 can be rotated at high speed with its own rotational inertia force, thus increasing the power generation efficiency of the alternator. Can do.

  In such a pulley unit A, vibrations from the engine are frequently received. However, since the above-described specific lubricant is used for the one-way clutch 10, the operation stability and wear resistance of the one-way clutch 10 are long-lasting. It is possible to contribute to the improvement of the reliability and life of the pulley unit A.

  In addition, this invention is not limited only to the said embodiment, Various application and deformation | transformation can be considered.

  (1) In the one-way clutch 10, the roller 13 can be a sprag or the like, and the coil spring 14 can be a leaf spring or an elastic piece.

  (2) In the above embodiment, the cam surface 12a of the one-way clutch 10 is formed on the inner ring 12 side. However, the present invention can also be applied to the one provided on the outer ring 11 side. However, the structure in which the cam surface 12a is provided on the inner ring 12 as in the above embodiment is suitable for use at high speed rotation, such as preventing the roller 13 from being unnecessarily removed from the locked position by centrifugal force even in the high speed rotation range. ing.

1 is a longitudinal front view of a one-way clutch according to an embodiment of the present invention. FIG. 1 is a developed plan view showing a part of the one-way clutch of FIG. Front view of the one-way clutch in FIG. Longitudinal side view of the pulley unit incorporating the one-way clutch of the above embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 One-way clutch 11 Outer ring 12 Inner ring 12a Cam surface 13 Roller 14 Cage 14a Pocket 15 Coil spring

Claims (3)

A one-way clutch that switches between a state in which two annular members arranged concentrically inside and outside in a radial direction are rotated synchronously and a state in which they are rotated relative to each other. An ester type or synthetic oil type having a coefficient (at 25 ° C.) of 12 GPa ^{−1 to} 64.4 GPa ⁻¹ , a consistency (at 25 ° C.) of 240 to 310, and a traction coefficient of 0.02 to 0.066. A one-way clutch comprising a base oil and a urea-based thickener.   The one-way clutch according to claim 1, wherein the state switching element is a roller that is rotatably disposed in a wedge-shaped space formed between the two annular bodies. .   The one-way clutch according to claim 1 or 2, wherein the lubricant and the base oil are added so that the consistency (at 25 ° C) of the lubricant is 240 to 310 and the traction coefficient (at 25 ° C) is 0.02 or more. The one-way clutch characterized by the compounding ratio with an agent being set.

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